I. Field of the Invention
This invention relates to imaging systems, and is particularly concerned with systems for producing integral or parallax panoramagramic images for direct viewing, projection onto a screen, or for recording on a sensitized recording surface.
II. Description of the Prior Art
Early attempts at producing a three-dimensional image had the disadvantage that the image necessarily had to be viewed through a stereoscope or through special spectacles. Subsequent research concentrated on systems where the image was viewed through a parallax barrier, but the actual production of the image continued to embody certain disadvantages.
Thus there was proposed a method of binocular stereopsis producing what is referred to as a parallax stereogram, but here the information contained in the image is simply twice that of a monocular system and as a result there is little freedom in the viewing position. To overcome this limitation it is necessary to increase the parallax information contained in the image. Instead of the two points of view used in the parallax stereogram, a multiplicity of views are used, and in some systems an infinite series representing all points of view between certain angular limits is used. This compound image is known as a parallax panoramagram. In the parallax panoramagram, the width to pitch ratio of the slit plate is much smaller than in the parallax stereogram, thus a wider viewing angle and more continuous spatial image can be achieved.
In its application to photography, recording a parallax panoramagram involves either a camera which moves along a horizontal track with the camera body distorting in such a way that a line drawn between the centre of the plate and the centre of the taking lens always passes through the centre of interest of the subject, or a multi-lensed camera with any appropriate number of lenses each simultaneously taking a photograph from a slightly different position. The disadvantage of the first method is that moving objects cannot be photographed and the camera mechanism is complex, while the second requires very accurately registered printing to produce the final 3-D image which is not a continuous panorama but a finite number of views which equal the number of original lenses. This inevitably produces an effect known as `flipping` to occur when viewing angle is changed, that is the observed spot is switched from the image produced by one lens to that produced by an adjacent lens.
To overcome these problems, a method has been proposed using a fixed, large aperture lens. If the lens has a wide aperture the single lens may collect the necessary picture information of the object viewed from various and continuous directions and the image may be directly recorded onto the photographic plate placed behind a slit plate. This method works well, however, the image recorded is in fact pseudoscopic, that is, a spatial image is produced which is entirely inverted in depth like a hologram viewed from the wrong side. Also the parallax barrier which was proposed to be used has a number of drawbacks both in recording and viewing a spatial image. In recording, it is the problem of the diffraction of light passing through a fine slit which causes a loss of image definition and available light, while in viewing it is the marked darkening of the image plus the annoyance of the grid's presence.
Some of these problems were overcome with the development of plastic technology which allowed a choice of clear materials which could be formed into lensed sheets. The lensed sheet collects the parallax information far more efficiently than the parallax barrier, and is much less obtrusive when viewing the image. Consequently the grid plate was replaced by the more efficient lensed sheet. However, the problem is that the systems available involve a two stage process one to record a pseudoscopic image and the other to project an orthoscopic image, and suffer due to image deterioration and the coarseness of the grid which limits the stereoscopic depth factor.
The object of the present invention, is to provide a method of and equipment for the direct production of integral or parallax orthoscopic panoramagramic images of improved quality and wider practical application than hitherto.